佛山市土地资源可持续利用探讨

土地资源的持续利用是实现生态、经济和社会可持续发展的基础。着重分析了广东省佛山市土地利用现状特点及存在问题,并在此基础上,提出土地可持续利用的对策与建议。农业用地应采取用地与养地相结合,改善农业生产条件,努力提高单产水平,优化农业用地结构,建设农业生产基地,发展外向型农业,因地制宜地开发未利用土地资源;对非农用地要做好建设用地需求预测工作,统筹规划,城镇用地内函与外延并重;合理调整农业和非农业用地结构;加大土地资源管理的力度,明晰土地产权,完善土地管理制度等。     

螺旋藻多糖的药理作用研究

螺旋藻多糖（Ｐｏｌｙｓａｃｃｈａｒｉｄｅ ｏｆ Ｓｐｉｒｕｌｉｎａ）是从螺旋藻中提取的一种无毒的天然产物,具有多种生物学活性。为进一步探讨螺旋藻多糖的作用,本文以小鼠为动物模型,观察极大藻多糖对小鼠生物功能的影响。螺旋藻多糖可以提高受γ射线致死剂量照射的小鼠３０天内的存活率促进小鼠多能干细胞和造血祖细胞的增殖和分化;促进受到辐射损伤的小鼠造血系统的恢复,增强小鼠的抗辐射能力。螺旋藻多糖可以提高小鼠     

Drosophila Myt1 is a Cdk1 inhibitory kinase that regulates multiple aspects of cell cycle behavior during gametogenesis

The metazoan Wee1-like kinases Wee1 and Myt1 regulate the essential mitotic regulator Cdk1 by inhibitory phosphorylation. This regulatory mechanism, which prevents Cdk1 from triggering premature mitotic events, is also induced during the DNA damage response and used to coordinate cell proliferation with crucial developmental events. Despite the previously demonstrated role for Myt1 regulation of Cdk1 during meiosis, relatively little is known of how Myt1 functions at other developmental stages. To address this issue, we have undertaken a functional analysis of Drosophila Myt1 that has revealed novel developmental roles for this conserved cell cycle regulator during gametogenesis. Notably, more proliferating cells were observed in myt1 mutant testes and ovaries than controls. This can partly be attributed to ectopic division of germline-associated somatic cells in myt1 mutants, suggesting that Myt1 serves a role in regulating exit from the cell cycle. Moreover, mitotic index measurements suggested that germline stem cells proliferate more rapidly, in myt1 mutant females. In addition, male myt1 germline cells occasionally undergo an extra mitotic division, resulting in meiotic cysts with twice the normal numbers of cells. Based on these observations, we propose that Myt1 serves unique Cdk1 regulatory functions required for efficient coupling of cell differentiation with cell cycle progression.     

Capitalizing on multi-element interactions through balanced nutrition — A pathway to improve nitrogen use efficiency in China,India and North America

A viable option for increasing nitrogen (N) use efficiency and mitigation of negative impacts of N on the environment is to capitalize on multi-element interactions through implementation of nutrient management programs that provide balanced nutrition. Numerous studies have demonstrated the immediate efficacy of this approach in the developing regions like China and India as well as developed countries in North America. Based on 241 site-years of experiments in these countries, the first-year N recovery efficiency (RE) for the conventional or check treatments averaged 21% while the balanced treatments averaged 54% RE, for an average increase of 33% in RE due to balanced nutrition. Effective policies to promote adoption are most likely those that enable site-specific approaches to nutrient management decisions rather than sweeping, nation-wide incentives supporting one nutrient over another. Local farmers, advisers and officials need to be empowered with tools and information to help them define necessary changes in practices to create more balanced nutrient management.

     

Spatial coexistence of phytoplankton species in ecological timescale

The species diversity of phytoplankton is usually very high in wild aquatic systems, as seen in the paradox of plankton. Coexistence of many competitive phytoplankton species is extremely common in nature. However, experiments and mathematical theories show that interspecific competition often leads to the extinction of most inferior species. Here, we present a lattice version of a multi-species Lotka–Volterra competition model to demonstrate the importance of local interaction. Its mathematical equilibrium is the exclusion of all but one superior species. However, temporal coexistence of many competitive species is possible in an ecological time scale if interactions are local instead of global. This implies that the time scale is elongated many orders when interactions are local. Extremely high species diversity of phytoplankton in aquatic systems may be maintained by spatial coexistence in an ecological time scale.Tatsuo Miyazaki, Kei-ichi Tainaka, and Jin Yoshimura contributed equally to this study.     

Characterization of two novel KRAB-domain-containing zinc finger genes, ZNF460 and ZNF461, on human chromosome 19q13.1-->q13.4

This study reports the cloning and characterization of two novel human zinc finger protein cDNAs (ZNF460 and ZNF461) from a fetal brain cDNA library. The ZNF460 cDNA is 3,135 bp in length encoding a 562-amino-acid polypeptide and the ZNF461 cDNA is 2,548 bp encoding a 563-amino-acid protein. Both of the proteins contain a KRAB A+B box and eleven C2H2 type zinc finger motifs. ZNF461 shows high similarity with the rat GIOT-1 gene (GIOT1). The ZNF460 gene mapped to 19q13.4 with 3 exons, and ZNF461 mapped to 19q13.1 with 6 exons. Both of the two genes are ubiquitously expressed in normal human tissues and the abundance of the ZNF460 mRNA is relatively low.     

Angiotensin-(1-7) Attenuates Kidney Injury Due to Obstructive Nephropathy in Rats

Background

Angiotensin-(1–7) [Ang-(1–7)] counteracts many actions of the renin-angiotensin-aldosterone system. Despite its renoprotective effects, extensive controversy exists regarding the role of Ang-(1–7) in obstructive nephropathy, which is characterized by renal tubulointerstitial fibrosis and apoptosis.

Methods

To examine the effects of Ang-(1–7) in unilateral ureteral obstruction (UUO), male Sprague-Dawley rats were divided into three groups: control, UUO, and Ang-(1–7)-treated UUO rats. Ang-(1–7) was continuously infused (24 μg/[kg·h]) using osmotic pumps. We also treated NRK-52E cells in vitro with Ang II (1 μM) in the presence or absence of Ang-(1–7) (1 μM), Mas receptor antagonist A779 (1 μM), and Mas receptor siRNA (50 nM) to examine the effects of Ang-(1–7) treatment on Ang II-stimulated renal injury via Mas receptor.

Results

Angiotensin II (Ang II) and angiotensin type 1 receptor (AT₁R) protein expression was higher in UUO kidneys than in controls. Ang-(1–7) treatment also decreased proapoptotic protein expression in UUO kidneys. Ang-(1–7) also significantly ameliorated TUNEL positive cells in UUO kidneys. Additionally, Ang-(1–7) reduced profibrotic protein expression and decreased the increased tumor growth factor (TGF)-β1/Smad signaling present in UUO kidneys. In NRK-52E cells, Ang II induced the expression of TGF-β1/Smad signaling effectors and proapoptotic and fibrotic proteins, as well as cell cycle arrest, which were attenuated by Ang-(1–7) pretreatment. However, treatment with A779 and Mas receptor siRNA enhanced Ang II-induced apoptosis and fibrosis. Moreover, Ang II increased tumor necrosis factor-α converting enzyme (TACE) and decreased angiotensin-converting enzyme 2 (ACE2) expression in NRK-52E cells, while pretreatment with Ang-(1–7) or A779 significantly inhibited or enhanced these effects, respectively.

Conclusion

Ang-(1–7) prevents obstructive nephropathy by suppressing renal apoptosis and fibrosis, possibly by regulating TGF-β1/Smad signaling and cell cycle arrest via suppression of AT₁R expression. In addition, Ang-(1–7) increased and decreased ACE2 and TACE expression, respectively, which could potentially mediate a positive feedback mechanism via the Mas receptor.